1. Field of the Invention
The subject of this invention is a method and apparatus to reduce puckering in machine sewn seams.
It is known to form on a work piece a line of machine stitching substantially free from puckering by placing a stitch-engaging element of a width less than the length of a stitch to project across the line of stitching in advance of the sewing position, allowing the element to remain in position across the line of stitching until a stitch has been formed overlying the element then withdrawing the element from below the formed stitch.
All the known apparatus intended to reduce or eliminate puckering has incorporated a stitch-engaging element in the form of a rigid finger operatively connected to the sewing machine mechanism and synchronized therewith to move transversely across the line of stitching immediately before each stitch is formed and then to be withdrawn from below the formed stitch immediately after the stitch is formed.
Such known apparatus has either to be built into the machine during manufacture of the machine or if it is to be fitted to an existing machine extensive modification of the machine is required to adapt it to receive the stitch-engaging element and its operating mechanism.